Lateral III-nitride devices including a vertical gate module
A lateral III-N device has a vertical gate module with III-N material orientated in an N-polar or a group-III polar orientation. A III-N material structure has a III-N buffer layer, a III-N barrier layer, and a III-N channel layer. A compositional difference between the III-N barrier layer and the III-N channel layer causes a 2DEG channel to be induced in the III-N channel layer. A p-type III-N body layer is disposed over the III-N channel layer in a source side access region but not over a drain side access region. A n-type III-N capping layer over the p-type III-N body layer. A source electrode that contacts the n-type III-N capping layer is electrically connected to the p-type III-N body layer and is electrically isolated from the 2DEG channel when the gate electrode is biased relative to the source electrode at a voltage that is below a threshold voltage.
1. A III-N device, comprising:
a III-N material structure over a substrate , wherein the III-N material structure comprises a III-N buffer layer, a III-N barrier layer, and a III-N channel layer, wherein a compositional difference between the III-N barrier layer and the III-N channel layer causes a 2DEG channel to be induced in the III-N channel layer;
a p-type III-N body layer over the III-N channel layer in a source side access region of the device but not over the III-N channel layer in a drain side access region of the device; and
an n-type III-N capping layer over the p-type III-N body layer;
a source electrode, a gate electrode, and a drain electrode each over the III-N material structure on a side opposite the substrate;
wherein the source electrode contacts the n-type III-N capping layer and is electrically connected to the p-type III-N body layer, and the drain electrode contacts the III-N channel layer; and
wherein the source electrode is electrically isolated from the 2DEG channel when the gate electrode is biased relative to the source electrode at a voltage that is below a threshold voltage of the device.
2. The device of claim 1 , wherein the III-N device is an N-polar device.
3. The device of claim 2 , wherein the III-N barrier layer is between the III-N channel layer and the III-N buffer layer.
4. The device of claim 1 , further comprising a gate insulator layer, wherein the gate insulator layer and the gate electrode are formed over a vertical or slanted sidewall of the p-type III-N body layer in a gate region of the device, the gate electrode further comprising a first portion extending towards the source electrode and a second portion extending towards the drain electrode.
5. The device of claim 4 , wherein the III-N device is configured such that an inversion channel is formed in the p-type III-N body layer adjacent to the gate insulator layer when the gate electrode is biased relative to the source electrode at a voltage greater than the threshold voltage of the device; and
the inversion channel electrically connects the source electrode to the 2 DEG channel while a positive voltage is applied to the drain electrode.
6. The device of claim 4 ; wherein
the III-N device is configured such that while the gate electrode is biased relative to the source electrode at a voltage greater than the threshold voltage of the device, a conductive device channel including the 2DEG channel extends continuously from the source electrode to the drain electrode; and
while the gate electrode is biased relative to the source electrode at a voltage less than the threshold voltage and the drain electrode has a positive voltage bias relative to the source electrode, the device channel is depleted of mobile charge in the gate region of the III-N device.
7. The device of claim 4 , further comprising a III-N layer structure between the gate insulator layer and the III-N body layer.
8. The device of claim 7 , wherein the III-N layer structure contacts the III-N capping layer in the source side access region and contacts the III-N channel layer in the drain side access region.
9. The device of claim 7 , wherein the III-N layer structure extends continuously between the source electrode and the drain electrode.
10. The device of claim 7 , wherein the III-N layer structure at least comprises a GaN layer in contact with the III-N body layer.
11. The device of claim 10 , wherein the III-N layer structure further comprises an Al x Ga 1-x N layer between the gate insulator layer and the GaN layer, wherein x is between 0.5 and 1.
12. The device of claim 4 , wherein an angle between the vertical or slanted sidewall of the III-N body layer and a top surface of the III-N material structure is between 20° and 80°.
13. The device of claim 1 , further comprising an AlN layer having a thickness in a range of 0.5 nm to 5 nm between the III-N body layer and the III-N material structure.
14. The device of claim 1 , further comprising an AlN layer having a thickness in a range of 0.5 nm to 5 nm between the III-N body layer and the III-N capping layer.
15. The device of claim 1 , wherein the source electrode is directly contacting and electrically connected to the p-type III-N body layer.